Geomorphological Markers Research Articles

Palaeomagnetic and mineral magnetic analyses of the Deckenschotter of northern Switzerland and southern Germany

The Deckenschotter is a fluvial to glaciofluvial gravel unit in northern Switzerland and southern Germany. The deposits are considered the oldest preserved glacial to interglacial Quaternary deposits in the northern Alpine foreland and are thus important geomorphological markers for landscape evolution. Nevertheless, the age of the deposits is only approximately known and subject to controversial debates. This study presents the results of an extensive palaeomagnetic investigation carried out on intercalated fine-grained sediments at 11 sites of the Höhere Deckenschotter (HDS) and at 5 sites of the Tiefere Deckenschotter (TDS). The HDS show reversed and normal magnetisations, indicating deposition > 0.773 Ma, while the TDS exhibit only normal directions. Age constraints for the different sites are discussed in the light of evidence from other studies. The study therefore clearly supports the efforts to determine the age of the Deckenschotter. As data from previous palaeomagnetic studies on the HDS and TDS have not been published or preserved, this is in fact the only data-based palaeomagnetic study available.

The Response of Sandstone Sea Cliffs to Holocene Sea-Level Rise by Means of Remote Sensing and Direct Surveys: The Case Study of Punta Licosa Promontory (Southern Italy)

Punta Licosa promontory is located in the northern part of the Cilento coast, in the southern Tyrrhenian basin. This promontory is bordered by sea cliffs connected to a wide shore platform sloping slightly towards the sea. This area has been considered stable at least since Late Pleistocene, as testified by a series of evidence well known in the literature. The aim of this research is to reconstruct the main coastal changes that have occurred in this area since the middle Holocene by means of the literature data, aerial photo interpretation, satellite images, GPS measurements, direct underwater surveys, GIS elaborations of high-resolution DTMs, bathymetric data and high-resolution orthophotos taken by UAV. Particular attention was paid to the wide platform positioned between −7.2 ± 1.2 m MSL and the present MSL, this being the coastal landform interpreted as the main consequence of sea cliff retreat. The elevation of this landform was compared with the GIA models calculated for the southern Tyrrhenian area, allowing establishing that it was shaped during the last 7.6 ± 1.1 ky BP. Moreover, the interpretation of archaeological and geomorphological markers led to the reconstruction of the shoreline evolution of this coastal sector since 7.6 ky BP. This research evaluates the cliff retreat under the effect of Holocene RSL variation on Cilento promontories, located in the western Mediterranean and characterised by the presence of monophasic platforms, and the applied method can be considered more effective and less complex and expensive if compared to other effective approaches such as those based on the usage of cosmogenic nuclides.

A comparative study of bedrock fault scarps by s-UAV and t-LiDAR: Insights into site selection criteria for paleo-seismology studies

Normal fault scarps, as classical topographic features and geomorphological markers along mountain range-fronts, form in consolidated bedrock due to faulting in extensional settings. They generally preserve more complete records of paleo-earthquakes than fault scarps in unconsolidated sediments. The reconstruction of paleo-seismic history from a bedrock fault scarp in terms of the times, co-seismic slips and ages by a combination of quantitative morphological analysis, TCNs dating and other physical/chemical index has been proven feasible by several previous studies. However, this success heavily relies on a suitable site selection along the bedrock fault scarp because geomorphic processes are also capable exhuming the fault surface, i.e., an erosion-origin fault surface. To distinguish between tectonic- and fault-origin fault surfaces, four bedrock fault surfaces (MJYC, NMZC, DYC and SYC) in the northern Shanxi Rift have been targeted to carry out a comparative study by combining small unmanned aerial vehicle (s-UAV) surveys and terrestrial laser scanning (TLS). The results can be classified into two groups according to their quantified morphological characteristics and exposed ways. For the NMZC and SYC group, which are in elevated areas away from gullies, the quantitative morphological analysis shows that both bedrock fault surfaces have the characteristics of vertical segmentation. This kind of segmentation indicates that the fault surfaces may be exhumed by repeated seismic events, and the corresponding co-seismic slips are determined by the height of these segments. For the MJYC and DYC group, the quantitative morphology shows a gradually-changing characteristic without segmentation. This gradually-changing characteristic indicates an erosional exposure mode from geomorphic processes, and accordingly the paleo-seismic information cannot be extracted. Thus, results from this study highlights the importance of selecting a suitable study site when conducting paleo-seismic research on bedrock faults. Based on experience obtained in this study combined with previous cases, we propose the characteristics of bedrock fault surfaces suitable for extracting paleo-seismic information and corresponding identification principles. Finally, a general workflow for paleo-earthquake history reconstruction from bedrock fault scarps is proposed to promote paleo-earthquake study in bedrock areas.

36Cl exposure dating of glacial features to constrain the slip rate along the Mt. Vettore Fault (Central Apennines, Italy)

The Central Apennines are among the most seismically active regions in Italy. This region is affected by an extension accommodated by active normal faults. Those faults with high seismogenic potential hosted Mw > 6 shallow damaging earthquakes, such as the Mw 6.5 event of Oct. 30, 2016. Although fault slip rates are crucial to seismic hazard assessments, in the Central Apennines, slip rate assessments encompassing several seismic cycles (> 10 ka) are sparse. This is particularly true for the Mt. Vettore-Mt. Bove Fault system that ruptured during the mainshocks of the 2016–2017 seismic sequence. In this study, we present new geochronological constraints of offset geomorphological markers along the northern portion of the fault system on the Mt. Porche Fault segment using in-situ produced 36Cl cosmogenic nuclides. Offset measurements were made using a 5-cm resolution DEM obtained through a drone survey and constrained a fault scarp height of 15.5 ± 1.4 m and a maximal cumulative offset estimated between 32 and 40.5 m. Samples were collected from the Valle Lunga terminal moraine at 1710 m asl and yielded 36Cl exposure ages of 12.7 + 2.2/−1.9 ka, while the abraded surface, located on top of the tectonic scarp yielded 36Cl exposure ages of 23.4 + 5.3/−4.3 ka. Using the fault scarp height and the exposure age of this abraded surface, we constrained a minimum vertical fault slip rate of 0.7 + 0.2/−0.1 mm/yr. Assuming the offset started to accumulate when climate conditions allowed the scarp preservation, we constrained a maximal vertical slip rate of 1.2 ± 0.2 mm/yr along the main fault of the Mt. Vettore-Mt. Bove Fault system. This rate is higher than those previously obtained from trenches along secondary branches of the Mt. Vettore-Mt. Bove Fault system. Besides, the yielded chronology for the last glacial maximum in that area at ~23 ka is in good agreement with the timing previously proposed for the LGM in the Apennines.

Active folding in the Tenes region (Tell Atlas, Algeria): modelling the 1922 earthquake fault-related fold (Mw 6.2)

We study the Tenes Abou El Hassan (TAEH) fault-related fold of the Tell Atlas (the site of the 1922 Mw 6.2 earthquake) using field investigations combined with satellite image processing. The 1922 earthquake is also revisited through previous reports, publications and contemporaneous newspapers in order to locate the area of maximum ground motion and its relation to the active TAEH fault-related fold. The analysis of high-resolution (0.5 m) satellite imagery (panchromatic Pleiades tri-stereo images) allows the accurate study in tectonic geomorphology and the characterization of active and seismogenic deformation. High-resolution DEMs obtained from Pleiades images highlight alluvial and marine terraces with cumulative uplift during the Upper Pleistocene–Holocene period and allowed the identification of geomorphological markers along the active fold with recognition of complex tectonic structures. The fault-related fold is modelled using both elastic (Okada 1992) and kinematic (Trishear) approaches using balanced cross-sections that reveal 1.2 mm/year shortening rate during the Upper Pleistocene–Holocene. Uplift rate calculated using marine and alluvial terrace altitudes is ~0.3 mm/year during the Upper Pleistocene along the Allalah Quaternary basin and the coastal zone reaching ~1 mm/year during the Holocene. The earthquake geology and correlation between surface deformation and seismotectonic modelling provides additional constraints on the 1922 earthquake fault parameters and related seismic hazard assessment in the Tell Atlas of Algeria.

Cosmogenic data about offset uplifted river terraces and erosion rates: implication regarding the central North Anatolian Fault and the Central Pontides

River terraces are geomorphological markers recording deformation. Here, we use four strath and fill river terraces along the Kızılırmak River in Turkey to unravel the deformation along the convex arc formed by the central North Anatolian Fault (NAF), a continental transform fault. 10Be, 26Al, 36Cl cosmogenic exposure ages of T3 and T2 strath terraces constrain their formation at 83 ± 15 ka and 67 ± 7 ka, respectively. We evidence frost-cracking during humid cold periods that bought younger carbonate cobbles on both terraces. T1, a younger fill terrace was probably emplaced during the MIS3 (30–40 ka) aggradational period or during the last glacial–interglacial transition. T0, the most recent fill terrace, was incised shortly before the 1668 earthquake based on 14C dating. It records a cumulated 14 ± 2 m offset linked to the 1943 and 1668 earthquakes. T3 shows a maximum offset of ~ 845 m and constrains a 10 mm/year geological slip rate that is lower than Holocene slip rates. It suggests temporal change in slip rates along the NAF. T2 and T3 also evidenced an uplift of 1 mm/year induced by transpressive deformation accommodated close to the NAF. Compared to the 0.28 mm/year obtained to the north, a larger portion of the shortening in the Central Pontides is accommodated close to the driving plate boundary. We also evidenced high cosmogenic-based erosion rates in Pontides during the Holocene, and even higher rates during T3 planation. Erosion rates were combined with present-day relief to infer a first-order minimal shortening of 12–16 km using simple mass balance principles in the Central Pontides. This long-term shortening is larger than the one induced by the Anatolian rotation suggesting a far field effect of the collision.

Slip rate determined from cosmogenic nuclides on normal-fault facets

AbstractFacets are major topographic features built over several 100 k.y. above active normal faults. Their development integrates cumulative displacements over a longer time frame than many other geomorphological markers, and they are widespread in diverse extensional settings. We have determined the 36Cl cosmogenic nuclide concentration on limestone faceted spurs at four sites in the Central Apennines (Italy), representing variable facet height (100–400 m). The 36Cl concentration profiles show nearly constant values over the height of the facet, suggesting the facet slope has reached a steady-state equilibrium for 36Cl production. We model the 36Cl buildup on a facet based on a gradual exposure of the sample resulting from fault slip and denudation. Data inversion with this forward model yields accurate constraints on fault slip rates over the past 20–200 k.y., which are in agreement with the long-term rate independently determined on some of those faults over the past 1 m.y. 36Cl measurements on faceted spurs can therefore constrain fault slip rate over time spans as long as 200 k.y., a time period presently undersampled in most morphotectonic studies.

Offset measurements along active faults based on the structure from motion method – A case study of Gebiling in the Xorkoli section of the Altyn Tagh Fault

This study reconstructs high-precision three-dimensional (3D) surface models using aerial imagery derived from unmanned aerial vehicles (UAVs) with the structure from motion (SfM) method. By combining automatic extraction and manual visual interpretation, the geometry of the active tectonics and offset channels along the fault is obtained. The offsets, caused by the motion of active tectonics, are measured via the retrodeformation of geomorphologic markers. This paper takes the tectonic geomorphology of Gebiling in the Xorkoli section of the Altyn Tagh fault as a case study. After the construction of 3D surface models using the UAV images and the SfM method, a data set of more than 200 offsets is obtained. The results indicate that 11 paleoearthquakes may have ruptured along the Gebiling section of the Altyn-Tagh fault.

Slip rates along the narrow Magallanes Fault System, Tierra Del Fuego Region, Patagonia

The up to 1000 km-long Magallanes Fault System (MFS) is the southernmost onshore strike-slip plate boundary and located between the South American and Scotia Plates. Slip-rates, a key factor for understanding neotectonics and seismic hazard are only available there from geodetic models. In this study, we present the first direct geologic evidence of MFS slip rates. Late-Cenozoic slip rates along the main MF is 5.4 ± 3.3 mm/yr based on lithologic geological separations found in regional mapping. Late-Quaternary deformation from offset geomorphologic markers was documented along the MFS in Chile and Argentina based on a combination of satellite mapping, fieldwork, and Structure from Motion (SfM) models developed from drone photography. By combining displacements observed in SfM models with regional Late-Quaternary dating, sinistral slip rates are 10.5 ± 1.5 mm/yr (Chile) and 7.8 ± 1.3 mm/yr (Argentina). By comparing our results with regional models, contemporary plate boundary deformation is narrow, approximately ~20–50 km wide from Tierra Del Fuego (TdF) and east (one of the narrowest on Earth), which widens and becoming more diffuse from Cabo Froward north and west (>100 km wide). In addition to the tectonic implications, these faults should be considered important sources of fault rupture and seismic hazard.

Comprehensive characterization of elevated coastal platforms in the north Iberian margin: A new template to quantify uplift rates and tectonic patterns

The Cantabrian margin, at the northern Iberian Peninsula, shows elevated coastal platforms extending from west to east for >200 km. These erosional surfaces are several kilometers wide, and are bounded inland by a paleoshoreline, and towards the sea by the retreating current cliff. The origin and evolution of these geomorphologic markers remains controversial, one of the main challenges arising from the difficulties in correlating the patchy distribution of the platforms and their variable heights along the margin due to lithological differences, local tectonism, and varying degrees of preservation. With the aim of understanding recent coastal evolution, a systematic quantitative GIS analysis of LiDAR elevation models (5 m resolution) was carried out along 4.000 km2 of the Cantabrian coast between 4.15°W and 7.30°W longitude. The coastline runs parallel to the Cantabrian Mountains, which are supported by an orogenic root present only beneath the eastern half of the coastline under study. The integration on the GIS template of the crust-mantle boundary as a controlling factor of landscape development has helped in the understanding of the recent evolution of the coastal platforms, and in the interpretation of previously unexplained features of their distribution.The two main outcomes of this multiscale approach are: 1) the correlation of most of the fragmented rasas as part of an original unique coastal platform along the Cantabrian margin, and 2) the differentiation of two sectors separated by a highly tectonized area associated to the Ventaniella fault. The western sector has one main, continuous surface showing a 0.08° tilt towards the west, sometimes interrupted by local and recent minor faults with net slips of meters to tens of meters. The eastern sector has several steps of erosional surfaces spread out at various heights without tilt. The Ventaniella fault, separating both sectors, produces an apparent vertical offset of 50 m in the main erosional surface. Our study shows that this fault also separates two distinct evolutions in the elevation of the coastal platform: (1) the western coast, which has risen continuously, probably in response to a lateral gradient in crustal thickness; and (2) the eastern coast, where uplift is discontinuous over time since several of these surfaces formed below the main paleoshoreline. The Cantabrian coast captures the influence that crustal structure has on the expression and evolution of geomorphologic markers at the surface. And vice versa, landform features at the surface can be very sensitive to differential crustal thickness while responding to the same external and climatic forces. In the context of the western European framework, our work provides a regional template within which future absolute geochronological dating can be based to improve our knowledge of the recent evolution of the Atlantic margins.

Late Quaternary paleo sea level geomorphological markers of opposite vertical movements at Salina volcanic island (Aeolian Arc)

AbstractRaised marine terraces and submerged insular shelves are used through an integrated approach as markers of relative sea level changes along the flanks of the Salina volcanic island (Aeolian Arc, southern Italy) for the purpose of evaluating its crustal vertical deformation pattern through time. Paleo sea level positions are estimated for the terrace inner margins exposed subaerially at different elevations and the erosive shelf edges recognized offshore at different depths. Compared with the eustatic sea levels at the main highstands (for the terraces) and lowstands (for the shelf edges) derived from the literature, these paleo sea level markers allowed us to reconstruct the interplay among different processes shaping the flanks of the island and, in particular, to quantify the pattern, magnitudes and rates of vertical movements affecting the different sectors of Salina since the time of their formation. A uniform uplift process at rates of 0.35 m ka−1 during the Last Interglacial is estimated for Salina (extended to most of the Aeolian Arc) as evidence of a regional (tectonic) vertical deformation affecting the sub‐volcanic basement in a subduction‐related geodynamic context. Before that, a dominant subsidence at rates of 0.39–0.56 m ka−1 is instead suggested for the time interval between 465 ka (MIS 12) and the onset of the Last Interglacial (MIS 5.5, 124 ka). By matching the insular shelf edges with the main lowstands of the sea level curve, a relative age attribution is provided for the (mostly) submerged volcanic centres on which the deepest (and oldest) insular shelves were carved, with insights on the chronological development of the older stages of Salina and the early emergence of the island. The shift from subsidence to uplift at the Last Interglacial suggests a major geodynamic change and variation of the stress regime acting on the Aeolian sub‐volcanic basement. © 2019 John Wiley & Sons, Ltd.

Investigating collapse structures in oceanic islands using magnetotelluric surveys: The case of Fogo Island in Cape Verde

One of the most remarkable natural events on Earth are the large lateral flank collapses of oceanic volcanoes, involving volumes of rock exceeding tens of km3. These collapses are relatively frequent in recent geological times as supported by evidence found in the geomorphology of volcanic island edifices and associated debris flows deposited on the proximal ocean floor. The Island of Fogo in the Cape Verde archipelago is one of the most active and prominent oceanic volcanoes on Earth. The island has an average diameter of 25 km and reaches a maximum elevation of 2829 m above sea level (m a.s.l.) at Pico do Fogo, a young stratovolcano located within a summit depression open eastward due to a large lateral flank collapse. The sudden collapse of the eastern flank of Fogo Island produced a megatsunami ~73 ky ago. The limits of the flank collapse were deduced as well from geomorphologic markers within the island. The headwall of the collapse scar is interpreted as either being located beneath the post-collapse volcanic infill of the summit depression or located further west, corresponding to the Bordeira wall that partially surrounds it. The magnetotelluric (MT) method provides a depth distribution of the ground resistivity obtained by the simultaneous measurement of the natural variations of the electric and magnetic field of the Earth. Two N-S magnetotelluric profiles were acquired across the collapsed area to determine its geometry and boundaries. The acquired MT data allowed the determination of the limits of the collapsed area more accurately as well as its morphology at depth and thickness of the post-collapse infill. According to the newly obtained MT data and the bathymetry of the eastern submarine flank of Fogo, the volume involved in the flank collapse is estimated in ~110 km3. This volume –the first calculated onshore– stands between the previously published more conservative and excessive calculations –offshore– that were exclusively based in geomorphic evidence. The model for the summit depression proposing two caldera collapses preceding the collapse of the eastern flank of Fogo is supported by the MT data.

Shoreline reconstruction of the submerged Minoan harbour morphology in the bay of Kato Zakros (Eastern Crete, Greece)

The Minoan centre of Kato Zakros flourished in a favourable geographical location, naturally fortified, in a leeward bay providing a natural harbour morphology. The submerged geomorphological markers of former sea levels define four distinct sea level stands, at −4.00±0.30m, −2.85±0.30m, −1.25±0.05m, and −0.50±0.05m. The dating of these sea levels was based on the gradual rise of the brackish groundwater, observed at the building relics and the water supply installations of the Palace, as well as on submerged coastal rock-cut structures. The oldest change in sea level is associated with the violent seismic disaster of the old Palace that occurred around 1600BCE. The destruction of the new Palace occurred around 1450BCE and is related with a strong seismic event that hit all the Minoan centres of Crete, but it did not cause any change in the relative sea level. The following sea level change is most likely related with the demise of the Minoan centres of Crete around 1200BCE. During the historical period, two changes in relative sea level occurred. The first change is linked with the 1604CE earthquake, and the most recent with the period of the last 400years. The palaeoshoreline reconstruction of the Kato Zakros bay revealed a natural morphology, shaped by an elongate beachrock slab on the northernmost part of the western coast. Coastal responses to sea level rise include: progressive shoreline retreat, submersion of the natural harbour morphology and coastal fishing installations, and flooding of the Palace relics.

From Doline Distribution to Tectonics Movements Example of the Velebit Mountain Range, Croatia

Clanek obravnava povezavo med tektonskimi silami in kraskimi povrsinskimi oblikami. Smer deformacij in napetosti v Velebitskem masivu smo izracunali na osnovi razporeditve vrtac z uporabo metode “center-center” (Ramsay, 1967; Fry 1979). 623 rezultatov lokalnih meritev smo vnesli v 2D model koncnih elementov, ki deluje v programskem okolju Castem 2000. Ta na osnovi deformacij izracuna tektonske pogoje, ki tem deformacijam ustrazajo. Rezultati se v veliki meri ujemajo z GPS meritvami in rezultati geoloskega kartiranja. The influence of tectonic forces on karst relief development has been studied using dolines as geomorphological markers. The strain and stress orientations have been calculated from the doline distribution, applying the centre to centre method (Ramsay, 1967; Fry, 1979). 623 local results have been obtained which were later injected into a 2D finite element model created in Castem 2 000 software. As the observed deformations are the consequence of the tectonic displacements, the numerical model tends to simulate the tectonic conditions, which are closely related to the observed deformations. The results were correlated with the GPS measurements as well as with the geological field mapping results and great coincidence was observed.

Chapter 3 Active tectonics in the central and eastern Azores islands along the Eurasia–Nubia boundary: a review

Abstract The geodynamic setting of the Azores archipelago, straddling the triple junction between the North America, Eurasia and Nubia plates, is reflected in frequent volcanic and tectonic activity. A review of neotectonics is presented for the islands forming the central and eastern groups of the Azores (Faial, Pico, São Jorge, Graciosa, Terceira, São Miguel and Santa Maria). The geometry and kinematics of active faults displacing stratigraphic and geomorphological markers of Pleistocene and Holocene age are presented. Slip-rates were determined using the available ages for the displaced markers. Maximum expected moment magnitudes were estimated using empirical correlations between magnitude and fault length, fault area and maximum observed surface displacement during surface-rupturing palaeoearthquakes. Neotectonic parameters show that the faults are in most cases very to moderately active, with slip-rates usually ranging from a few tenths of millimetres to a few millimetres per year, while maximum expected magnitudes vary from M w 6 to 7. These magnitudes are in agreement with the instrumental and historical seismic record in the region. Neotectonic data define a dextral transtensive stress regime acting on the region and contribute to characterizing the complexity of the geodynamic processes that dominate the western-most segment of the Eurasia–Nubia plate boundary.

Chapter 7 The rock coast of the Mediterranean and Black seas

Abstract Rock coasts and shore platforms are conspicuous landforms along the Mediterranean and Black Sea (MBS) coasts. These coasts have been fashioned by changes in sea level because of vertical movements of the land and variations in eustatic and isostatic sea-level. For this reason, the Quaternary evolution of MBS coasts has been extensively studied, even starting from geomorphological markers, while very few researches have addressed the processes related to their origin and evolution. Despite most of the Mediterranean coast being rocky, studies about rocky shore processes are almost completely lacking, except for limited areas. Data on sea cliff retreats have mainly been collected to study the susceptibility of cliff failures or to prevent landslides, in particular along shores used for tourism. Data on erosion rates and processes on shore platforms are generally scarce and restricted to limestone bedrocks. In this paper, we summarize the results of studies of rates and processes of rocky coasts of the countries overlooking the Mediterranean and Black Seas and review the current knowledge concerning rock coasts in the MBS area.

Tectonic beheading of fluvial valleys in the Maestrat grabens (eastern Spain): Insights into slip rates of Pleistocene extensional faults

Interaction between faulting and landscape evolution in regions of active tectonics allows us to use subtle geomorphological markers for estimating fault slip rates. Geomorphic features of two valleys connected with the bottom of the Alcalà de Xivert graben, at the Maestrat graben system (eastern Spain), suggest that they correspond to the lowest segments of ancient valleys whose original heads were located at the axis of the neighbouring Irta range. They were beheaded owing to displacement of the Torreblanca and Irta faults during a period of active extensional faulting in Middle Pleistocene times. These faults produced a negative inversion of the relief, sinking a narrow graben (the Ametler graben) at the middle of the Irta range whose alluvial infill buried the midsegments of the beheaded valleys. This hypothesis has been tested by applying two geomorphic indices, the Stream-gradient index (SL) and the Valley width/height ratio (Vf), as well as by considering surface and subsoil information about the sedimentary infill of the Ametler graben. From this evolutionary model, after reconstructing hypothetical longitudinal profiles of the ancient rivers, and taking into account a new absolute age obtained for the alluvial infill of the Ametler graben, slip rates at the northern segment of the Torreblanca fault have been approached. The throw rate has been constrained between a minimum of 0.04–0.07mm/year for the last 1.9 to 2.6Ma, and a maximum of 0.26–0.30mm/year for the last 253.3±18.0ky. These values are comparable to those averaged on other active faults in the central-eastern Iberian Chain for the overall Late Pliocene–Pleistocene times. Nevertheless, the Torreblanca fault shows exceptionally high activity within the context of the Maestrat and Catalonian grabens, which can explain its deep imprint in landscape evolution.

Biological indicators of relative sea level change during the last 2 ka on the islands of Vis, Ravnik and Biševo in Croatia

On the particularly exposed sites on rocky coasts of islands Vis, Ravnik and Bisevo in Croatia, biogenic littoral rims built by the coralline rhodophyte Lithophyllum lichenoides can be found. The presence of thick and well-developed Lithophyllum rims, considered to be precise (±10 cm) sea-level indicator, points directly to the rising sea-level environment. Up to now five locations have been studied: 3 on the island of Vis, 1 on Ravnik and 1 on the island of Bisevo. Biogenic rims were mapped, measured and sampled for 14C dating. Three of the researched algal structures have two dominant levels: the upper one, 6 m long and 40 to 150 cm wide, and the lower one with a maximal extension of 40 cm. The surface of the lower level is 60 cm below the recent one. The thickness of each level at its most protruding part is around 15 cm. Today, on the relatively horizontal surface of the upper level algal rims the process of biodestruction prevails over bioconstruction. Living talli of Lithophyllum lichenoides were found only in small patches at the highest position on the horizontal surface of the rim and along its upper limit. Such a situation could clearly be connected to the recent acceleration of the sea-level rise as mentioned by Laborel et al., 1994. The prograding morphology of the algal rims points to the slowing of the sea-level rise starting at around −1 m below the MSL, when the algal rims began to develop. Based on the archaeological markers from 2300 ± 100 yr BP till around 1900 ± 100 yr BP the rate of relative sea level change was around 0.89 mm/yr (Faivre et al., in press) and then, according to the 14C dated algal samples it slowed down to 0.45 mm/yr from around 1450 yr BP till today. The obtained results have been compared not only with archaeological markers, e.g. submerged port remains of the ancient Issa harbour on the island of Vis, but also with geomorphological sea-level markers, as well as with other available data along the Croatian coast.

Inception of activity and slip rate on the Main Recent Fault of Zagros Mountains, Iran

We used geological, geomorphological markers, pull‐apart basins, and drainage patterns to explore totally a new more accurate strike‐slip offset on the Main Recent Fault (MRF) of the Zagros Mountains in SW Iran. The MRF has a NW–SE strike that is among the most important structural features within the Arabian–Iranian continental collision zone. Inception of the MRF has been suggested to be related to the slab break‐off underneath the Zagros during the last 10–5Ma. We conclude that the maximum total right‐lateral offset on the MRF is about 16km, leading to a slip rate of about 1.6–3.2mmy−1. These figures for the fault inception time and slip rate are consistent according to geodetic estimates and three‐dimensional mechanical modeling.

Vertical movements in NE Sicily and its offshore: Outcome of tectonic uplift during the last 125 ky

New data in the coastal area between Acquedolci and Patti (northeastern Sicily, Italy) have been collected to calculate vertical tectonic rates in a key sector between the Kabilian–Calabrian and the Sicilian–Maghrebian chain. The comparison among marine geology data (multibeam and seismic reflection profiles) on the continental shelf-slope system and the radiocarbon ages on geomorphological markers collected during a coastal survey, provided new stratigraphic, geomorphological and biological data, contributing to the knowledge of the geological evolution of this sector for the last 125 ky.This coastal area is framed between two main structural features active during the Pleistocene in northern Sicily: the Kabilian–Calabrian Thrust Front (west of Acquedolci) and the Vulcano–Tindari Fault (east of Patti). The occurrence of these structural features, the former compressive, the latter transcurrent, confirms that the study area is tectonically active and “moves” vertically in differential mode. Fault systems separate blocks with different uplift rates both in onland and offshore areas. In the Gulf of Patti, the offshore area is subsiding, while contemporaneously uplift of the mainland can be observed. The study sector records the same uplift rates both during MIS 5.5 and the Holocene, in contrast to the other areas of Sicily.